1. Field of the Invention
The present invention relates to an adjustable wrench for quickly adjusting width of the jaw thereof. The width of the jaw of the wrench can be quickly adjusted to a desired size by simply moving a movable body of the wrench.
2. Description of the Prior Art
A conventional adjustable wrench comprises a movable body and a stationary body. A worm mechanism is provided at a lower portion of the movable body. A square hole is disposed in the stationary body to receive a section of the worm mechanism of the movable body. A worm gear is provided within the square hole to engage a worm of the movable body. When a user manually rotates the worm gear, the worm can move in a left-and-right direction corresponding to the rotation of the worm gear, which in turn drives the movable body to move in the same direction, thereby adjusting the width of a jaw of the wrench.
The adjustable wrench having the aforesaid configuration is relatively simple in construction and convenient for use. However, such a wrench has disadvantages that when the width required to be adjusted is relatively large, the worm gear must be turned frequently. For example, if a large size wrench is used in exploitation of oil where a relatively larger pipe or nut needs to be turned, it is necessary to turn the worm repeatedly to give a full jaw travel. Furthermore, it is difficult to reliably hold an object by manually adjusting the width of the jaw.
In order to solve these problems, Chinese Patent No. CN2196532 with a title of “a quickly adjustable double ended wrench”, issued on May 10, 1995, discloses an adjustable wrench of which the width of the jaw can be quickly adjusted. During the adjustment of the width of the jaw, the worm and the worm gear are first separated by one hand, then the movable body is adjusted to a desired position by the other hand, and finally the worm and the worm gear should be arranged to engage with each other. This kind of wrench overcomes to some extent the abovementioned defects of the adjustable wrench. However, the wrench must be operated with both hands, which could be further improved.
Moreover, an adjustable open end wrench is also disclosed in U.S. Pat. No. 3,555,939. A slot is provided along one side of a handle of a stationary body of the adjustable wrench to communicate with a cavity for receiving a worm gear. A helical shaft is provided in the slot. A bevel gear is provided at an end of the helical shaft close to the cavity to intermeshes with another bevel gear disposed at an end of the worm. A thumb button control is provided at the handle, an end of which is slidable along a groove of the worm. In this way, while the thumb button control is pushed, the worm will rotate to in turn drive the movable body to move. This type of wrench can be adjusted by one hand. However, this adjustable open end wrench is relatively complex to construct and incurs a high cost.